Research On Pulse And Vibration Electrochemical Machining Of Aero-Engine Blades

Blade is one of the important components in aero-engine. The machining quality of blade affects the engine performance directly. Because of its special characteristics of complex structure and hard-to-cut materials, blade is very difficult to machine. Electrochemical machining(ECM) removes electrical conductive material via a controlled electrochemical anodic reaction regardless of its mechanical properties. It has such advantages as no electrode wear, good surface quality, regardless of the material hardness and ductility. It has become one of the main technologies for the machining of blade. In order to improve the accuracy of ECM blade, the precision ECM technology with pulsed voltage and electrode vibration was studied in this paper. The main research work as follows:(1) The processing scheme of ECM blade was put forward. Based on the characteristics of die forging blank of blade, such as big allowance range,poor blank consistency and minimum allowance, the alternate processing scheme of DC ECM and pulsed voltage composite electrode vibration ECM in one process was put forward. By using this processing scheme, the machining precision and efficiency of ECM blade can be improved simultaneously.(2) The feeding distances ratio of DC ECM and pulsed voltage composite electrode vibration ECM was identified. According to the ECM theory of transition process and genetic irregularity, the ratio of feeding distances in DC and pulsed voltage composite electrode vibration ECM was identified reasonably. The Processing efficiency was significantly increased with this feeding distances ratio.(3) The optimization parameters of pulsed voltage composite electrode vibration ECM was obtained. The machining gap and surface roughness were selected as the evaluation observation of orthogonal experiment results. The optimal combination of process parameters was obtained by using the gray correlation analysis method. The results showed that the optimized parameters could reduce machining gap and improve the surface quality of ECM.(4) A new design method of flow field for ECM turbine blade was proposed. In conventional design method, the flow fields are always extended along a certain direction. When ECM of complex curved blades with big twist angles, significant differences of inflow angle will affect the stability of the flow field. It is likely to cause short circuit in ECM. In order to improve the stability of the flow field, a new design method of flow field was proposed to ECM turbine blade. The new flow field was analyzed by finite element method. The result showed that new flow field was more stable than conventional flow field during the ECM.(5) Experimental study on ECM of turbine blade was carried out. By using the suggested feeding distances ratio, optimized parameters and flow field, the experiments of ECM turbine blade were carried out. Finally, the profile errors of machined specimen were better than 0.1mm.